Orthodontics is a specialty of dentistry that is concerned with improvement of the general appearance of a patient's teeth and also the correction of malocclusions, crookedness and other flaws of the teeth. Orthodontic braces are devices that are placed on a patient's teeth by a dental practitioner. In an orthodontic brace, wires interact with brackets to move teeth to a desired position. Often, such orthodontic braces are periodically adjusted by the dental practitioner to help align and straighten the teeth. Treatment by the dental practitioner may help in repositioning the teeth to correct flaws and improve the general appearance of the patient.
Another method of orthodontic treatment may use a series of clear, removable teeth aligners as an alternative to orthodontic braces. The series of aligners are successively worn by the patient to reposition the teeth to correct flaws. During a treatment process, a dental practitioner may prescribe a series of aligners, which are generally placed over the patient's teeth, to move one or more teeth from their original position to an aesthetically pleasing position. A series of aligners may be used to treat the patient because the degree of movement produced by an aligner is limited. Each aligner in a series may be designed to move one or more teeth over a portion of the entire distance towards the desired position. An aligner for orthodontic treatment is also referred to as an orthodontic aligner and it is a type of incremental position adjustment dental appliance.
In one mechanism for fabricating aligners, a computer generated design of a series of positive models corresponding to successive positions of a patient's teeth for achieving an aesthetic appearance of the patient's teeth may be generated. The positive model corresponds to a cast of the patient's teeth. The computer generated design may be used by a rapid prototyping mechanism that uses a three-dimensional printer, a stereolithography (SLA) machine, etc., to fabricate a series of positive models. Clear plastic which forms the aligners is molded over the positive models of the tooth configuration via a process referred to as thermoforming. In the thermal brining process a flat thermoplastic sheet is heated and deformed into the desired shape of the orthodontic aligners.